Modular tank system for a liquid reducing agent with a sump element and motor vehicle having the system

ABSTRACT

A modular tank system for a liquid reducing agent includes three modules. A first module has a tank with a first opening and an opposite second opening. A second module has a cap element for holding at least one discharge tube. A third module has a sump element. The cap element is disposed in the first opening and the sump element is disposed in the second opening. A motor vehicle having the modular tank system is also provided.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation, under 35 U.S.C. § 120, of copending International Application No. PCT/EP2009/006538, filed Sep. 9, 2009, which designated the United States; this application also claims the priority, under 35 U.S.C. §119, of German Patent Application DE 10 2008 046 630.1, filed Sep. 10, 2008; the prior applications are herewith incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates to a modular tank system for a liquid reducing agent which includes a sump element and in which the tank has three modules. The invention also relates to a motor vehicle having the modular tank system.

SCR systems are being used to a greater extent in motor vehicles due to higher requirements on emissions limits for pollutants from internal combustion engines. The SCR systems involve the use of a reducing agent, which must be stored, in particular in liquid form as a urea/water solution, in separate tank volumes. The volumes of the tanks for the reducing agent which are required in such a case are preferably in a range of from 3 to 10 liters, and up to 150 liters in the commercial vehicle sector. There is therefore a demand for tank shapes which must be matched to the widely varying spatial conditions in specific motor vehicles, especially when an SCR system is integrated in a supplementary manner into a motor vehicle as part of a retrofitting operation.

Tanks for liquid reducing agent regularly have discharge tubes, through which the liquid reducing agent can be discharged from the tank. The discharge tubes extend into the tank from an upper region of the latter, thus allowing the tank to be emptied to the maximum extent and, at the same time, ensuring that seals required to fix the discharge tube in the tank wall are, where possible, placed out of the reducing agent. Moreover, the discharge tube regularly has a heating device, through the use of which frozen reducing agent, of which there may be at least a small volume, can be melted and conveyed out of the tank through the discharge tube.

The discharge tube has adequate strength, especially with regard to the possible freezing of the reducing agent, ensuring that the discharge tube retains its full functionality over many years of use. In particular, it must be made sufficiently stiff, thus ensuring that the position of the tank discharge tube remains fixed. Due to the area of application of SCR systems in motor vehicles, it is necessary that the components of the system have a compact construction and, in particular, a diverse construction regarding the configuration thereof in the motor vehicle.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a modular tank system for a liquid reducing agent with a sump element and a motor vehicle having the system, which overcome the hereinafore-mentioned disadvantages and solve some of the highlighted problems of the heretofore-known systems and vehicles of this general type. In particular, the intention is to specify a modular tank system which, due to being produced from different modules, can be made very diverse for different applications. Moreover, the modular tank system has a sump element which can be produced in a simple and economical manner, has a low weight, is constructed to be suitable for stabilizing the position of a discharge tube and has an advantageous effect on a discharge itself. In particular, the aim is to ensure that the sump element can be used in as large a variety of tank shapes as possible by virtue of a spatially flexible accommodation of the discharge tube, thus eliminating costly customized structures of the individual components for different tank shapes.

With the foregoing and other objects in view there is provided, in accordance with the invention, a modular tank system for a liquid reducing agent. The tank system comprises at least three modules including a first module having a tank with a first opening and a second opening, a second module having a cap element disposed in the first opening for accommodating at least one discharge tube, and a third module having a sump element disposed in the second opening. The discharge tube is spatially or three-dimensionally fixed by the cap element and the sump element.

In this configuration, the first opening and the second opening of the tank are, in particular, round, thus allowing the cap element and/or the sump element to be turned relative to the tank. Moreover, there is at least one discharge tube disposed in the cap element, extending from the cap element into the tank and being accommodated by the sump element, which is, in particular, disposed opposite.

In this case, an opposite configuration of the sump element and the cap element means, in particular, that they can also be disposed at an angle relative to one another, in particular in adjacent wall sections of the tank as well.

The second module and, in particular, the cap element as well, preferably have a multi-piece construction and, in addition to the discharge tube, can accommodate further components, in particular a return line, which can direct excess reducing agent or reducing agent which is not needed from the SCR conduit system back into the tank, plus sensors and, if appropriate, control and/or measurement electronics. The discharge tube is preferably secured in the cap element in such a way that an exclusively transverse movement is required to introduce the discharge tube into the sump element. In particular, the cap element has a fastening element that can be rotated relative to the discharge tube and through the use of which the cap element can be connected to the tank, e.g. by way of a thread. This makes it possible, on one hand, even for discharge tubes that are not round or, on the other hand, even for several components together, to be introduced into the sump element. Moreover, the cap element has at least one sealing surface for sealing off the tank relative to the environment of the tank. In particular, two sealing surfaces are provided, being formed around the full circumference at different diameters. The cap element furthermore has at least one metal ring, which is preferably molded into the cap element. This metal ring is suitable, in particular, for stabilizing the sealing surfaces of the cap element in terms of roundness and flatness and making them durable. A metal ring of this kind is also preferably provided in the first opening of the tank and/or in the fastening element of the cap element.

The sump element is constructed to accommodate and fix the discharge tube, and it is also possible for other, additional elements extending through the tank, which are, in particular, disposed in the cap element, to be accommodated in a manner comparable to the discharge tube.

Spatial fixing of the discharge tube is achieved, in particular, by the fact that, once the cap element and the sump element have been fastened on the tank, the discharge tube can no longer be moved by the liquid reducing agent contained in the tank (due to shocks or the like which occur during operation). In particular, the discharge tube should remain in the same position in which it was disposed, even if the reducing agent freezes. Thus stresses, especially on the cap element and on the tank due to deflection of the discharge tube, which can lead to leaks in the tank and/or damage to the components (tank, cap element, sensors, conduits and electrics), are avoided.

The modular construction of the tank system makes it possible to combine various structures of the modules and, in particular, ensures that it is always possible to use the same second and third modules with the tank, given different structures of the first module, and to compensate for any differences in the position of the second and third modules in the tank through the use of the modules themselves. This provides not only a significant reduction in the number of parts while simultaneously allowing a high degree of adaptability to the spatial conditions in motor vehicles, but equally also ensures secure fixing and therefore sustained discharge of the reducing agent in all operating situations.

In accordance with another feature of the invention, the sump element forms the lowest point of the tank. This means, in particular, that the sump element regularly takes up the volume of reducing agent when the tank has been largely emptied, thus enabling the discharge tube to empty the tank, at least almost completely.

In accordance with a further feature of the invention, the sump element is formed as a separate plastic part. For the (preferred) case where the tank is manufactured from a plastic, the sump element should preferably be produced from a similar or identical material. Other potential materials that are preferred for the sump element and/or the tank are aluminum or stainless steel, in particular. Plastic is a suitable material for holding the urea/water solution even over a long period without showing signs of deterioration. As compared with metal tanks, the plastic sump element and/or tank are more economical and can be made lighter in weight.

In accordance with an added feature of the invention, the sump element is welded to the tank, yielding a material bond. A joint of this kind can be produced economically and can regularly be executed to provide a joint of maximum leak- tightness. This method of joining is suitable especially for use during the production of the tank. In this case, however, the position of the sump element relative to the cap or cover element is fixed and further modification of the position of the sump element can be achieved only with considerable effort.

In accordance with an additional feature of the invention, the sump element has structures which reduce movements of the liquid reducing agent in the region of the sump element. This means, in particular, that the movements occurring during the operation of the tank system are to a large extent avoided or reduced. At the same time, the sump element is, in particular, constructed in such a way that it can hold only a very small volume of reducing agent in comparison with the tank, having, in particular, a volume of less than 5% of the tank volume, particularly preferably less than 1%. This volume, which is small, is held in a region that is shielded from external flow movements of the reducing agent in the tank, thus enabling the discharge tube to convey the reducing agent without air inclusions or other disruptions. At the same time, this is intended to ensure that any measuring sensors that may be present can regularly determine reliable data, especially with regard to temperature, density, reflectance or refractive index, electrical conductivity and sound transmission. These values for the reducing agent should not be distorted by movements of the reducing agent.

Thus the structures in the sump element are constructed in such a way that an exchange of volume between the comparatively small volume of the sump element and that of the tank volume is to a large extent avoided and that, furthermore, the volume of the sump element is subdivided in such a way that flow movements are reduced to a large extent in this area as well.

In accordance with yet another feature of the invention, the sump element has a holder for the discharge tube, which holder is suitable for fixing a discharge tube disposed at an angle of 45° to 90° relative to the tank bottom. In this case, the angle between the discharge tube and the tank bottom is always an angle ≦90° between the center line of the discharge tube and the region of the tank bottom in which the sump element is accommodated. This structure of the holder for the discharge tube and, in particular, the round embodiment of the first and second openings of the tank, makes it possible to achieve a large number of tank shapes and positions for the cap element and the sump element using a standardized cap and sump elements. As a result, the sump element according to the invention is suitable for use in virtually all SCR systems, even those that are to be retrofitted.

The embodiment, in particular the round embodiment, of the openings in the tank to accommodate the cap element and the sump element ensures that the sump element and the cap element can regularly be aligned in one plane relative to one another, thus allowing secure fixing of the discharge tube.

In accordance with yet a further feature of the invention, the sump element has a holder for the discharge tube, which holder forms a fit or seat with the discharge tube. In this case, the fit or seat should be constructed, on one hand, with regard to the required retention forces and, on the other hand, with regard to the strength of the discharge tube and of the holder of the sump element and with regard to the assembly forces for the discharge tube. In particular, the fit or seat should be embodied as a press fit, as a transition fit or as a slight clearance fit. The discharge tube could thus expand, in particular into the sump element, if the fit were embodied as a transition fit or a slight clearance fit. This embodiment may be necessary in the case of tanks with a very rigid structure in order to compensate for stresses caused by the discharge tube or by the tank itself as a result of thermal expansion.

In accordance with yet an added feature of the invention, the sump element has a holder for the discharge tube, which holder itself has a chamfer that allows the discharge tube to be pushed into the holder. In this case, the chamfer serves, in particular, to enable the discharge tube to be mounted easily and securely in the sump element, thus eliminating the possibility of damage to the discharge tube or the cap element during assembly.

In accordance with yet an additional feature of the invention, the holder of the sump element for the discharge tube is constructed in such a way that adequate fixing of the discharge tube is ensured without using the entire length of the holder of the sump element. In particular, the holder of the sump element for the discharge tube has a length of at least 50 mm, preferably at least 150 mm. The proposed chamfer is, in particular, not included in these length data. Constructing the holder in this way makes it possible, in particular, to use discharge tubes of different lengths and/or tanks with different distances and angles between the first opening and the second opening. At the same time, however, care should be taken, in particular, to ensure that the discharge tube extends far enough into the sump element to allow reducing agent, that has been calmed in terms of flow, to be conveyed.

In accordance with again another particularly preferred feature of the invention, the modular tank system makes provision for the sump element to be embodied in one piece. In this case, “in one piece” means, in particular, that the sump element is composed of components that are connected to one another at least by a material bond or can be produced in one step, e.g. by casting (plastic diecasting). In particular, it is also possible for the sump element to be embodied in two pieces, with the sump element and the structures being produced, in particular, from different materials.

In accordance with again a further feature of the invention, a sump element, especially for use in modular tank systems according to the invention for a liquid reducing agent, is furthermore proposed.

With the objects of the invention in view, there is concomitantly provided a motor vehicle, comprising a modular tank system according to the invention.

Other features which are considered as characteristic for the invention are set forth in the appended claims, noting that the features presented individually in the claims can be combined in any technologically meaningful way and reveal further embodiments of the invention.

Although the invention is illustrated and described herein as embodied in a modular tank system for a liquid reducing agent with a sump element and a motor vehicle having the modular tank system, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a diagrammatic, side-elevational view of a motor vehicle with a tank;

FIG. 2 is a first cross-sectional view of a first sump element, which is taken along a line II-II of FIG. 3, in the direction of the arrows;

FIG. 3 is a second cross-sectional view of the first sump element, which is taken along a line III-III of FIG. 2, in the direction of the arrows; and

FIG. 4 is a cross-sectional view showing a sump element disposed in a tank.

DETAILED DESCRIPTION OF THE INVENTION

Referring now in detail to the figures of the drawing for explaining the invention and the technical field in more detail by showing particularly preferred structural variants to which the invention is not restricted and in which identical reference signs are used for identical objects, and first, particularly, to FIG. 1 thereof, there is seen a diagrammatic side view of a motor vehicle 17 with a modular tank system 26, which has at least three modules. A first module 4 includes a tank 2 with a first opening 5 and an oppositely disposed second opening 6. A second module 7 includes a cap element 8 which, as illustrated therein, has a discharge tube 9, a discharge line 19, a return line 20 and electric leads 21 which, in particular, supply electrical energy to any sensors that may be present or any control and measurement electronics that may be required. The tank 2 furthermore has a third module 10 which includes a sump element 1. In this case, the sump element 1 is disposed in the region of a tank bottom 13 in the second opening 6. The second opening 6 is disposed opposite the first opening 5 within the tank 2, enabling the discharge tube 9 to extend from the cap element 8 to the sump element 1 and be accommodated therein. The tank bottom 13 and a center line 25 of the discharge tube 9 form an angle 15 therebetween, more details of which will be given in the description of the other figures. The tank 2 has a tank volume 23 and the sump element 1 has a volume 24, with the volume 24 being small as compared with the tank volume 23.

FIG. 2 shows a diagrammatic cross section of a sump element 1 in a first side view, with a discharge tube 9 extending into the third module 10 of the tank 2, i.e. into the sump element 1. The sump element 1 represents a lowest point 11 of the tank 2, thus enabling the discharge tube 9 to empty the tank 2 to the greatest extent possible. The sump element 1 is furthermore subdivided by structures 14 which simultaneously form a holder 12 for accommodating and fixing the discharge tube 9 and are intended to largely reduce or completely avoid flow movements of a reducing agent 3. Also provided, in side walls of the sump element 1, are apertures 18, through which the reducing agent 3 can flow out of the tank volume 23 of the tank 2 into the volume 24 of the sump element 1, thus ensuring that the sump element 1 is full as far as possible, irrespective of the inclination of the tank 2, and holds the volume 24 of reducing agent 3 in the tank 2 just before complete emptying. At the same time, the volume 24 of the sump element 1 is delimited with respect to the tank 2 by the apertures 18 through which the reducing agent 3 can flow into the sump element 1. The cross-sectional plane of the sump element 1, which is described below and shown in FIG. 3, is indicated by a section line III-III.

FIG. 3 diagrammatically shows the sump element 1 according to FIG. 2 in a second side view, with the cross-sectional plane in which the sump element 1 is illustrated in FIG. 2 being indicated therein by a section line II-II. The discharge tube 9 extends into the sump element 1 almost as far as the lowest point 11 of the tank volume 23, which is held by the sump element 1. In this case, the structures 14 are shown partially sectioned, with the structures 14 in this case at least partially forming the holder 12, through which the discharge tube 9 is accommodated and fixed in the sump element 1. The apertures 18, which are furthermore illustrated in the side walls of the sump element 1 at the level of the tank bottom 13, are intended to allow the reducing agent 3 to flow out of the tank volume 23 surrounding the sump element 1.

FIG. 4 diagrammatically shows the sump element 1 of the third module 10 in a third side view, with the discharge tube 9 in this case being disposed at an angle 15 between the center line 25 of the discharge tube 9 and the tank bottom 13. The sump element 1 is connected to the tank 2 or the tank bottom 13 by a flange 22. In this case, the discharge tube 9 is illustrated with an adapted shape, thus making almost complete emptying of the volume 24 possible and making it possible to even pump reducing agent 3 contained in the sump element 1 at the lowest point 11 of the tank 2 out of the tank 2. This is not always necessary. In contrast, it is also possible to provide a standardized discharge tube 9 which can empty the volume 24 in the sump element 1 at least to a very large extent. The sump element 1 has a chamfer 16 on the holder 12 thereof for the discharge tube 9, which makes it easier to push the discharge tube 9 into the sump element 1. 

1. A modular tank system for a liquid reducing agent, the tank system comprising: at least three modules including: a first module having a tank with a first opening and a second opening; a second module having a cap element disposed in said first opening for accommodating at least one discharge tube; and a third module having a sump element disposed in said second opening; said discharge tube being spatially fixed by said cap element and said sump element.
 2. The modular tank system according to claim 1, wherein said sump element forms a lowest point of said tank.
 3. The modular tank system according to claim 1, wherein said sump element is formed as a separate plastic part.
 4. The modular tank system according to claim 1, wherein said sump element is welded to said tank with a material bond.
 5. The modular tank system according to claim 1, wherein said sump element has structures reducing movements of the liquid reducing agent in vicinity of said sump element.
 6. The modular tank system according to claim 1, wherein said tank has a tank bottom, and said sump element has a holder for said discharge tube, said holder being configured for fixing said discharge tube at an angle of 45 to 90° to said tank bottom.
 7. The modular tank system according to claim 1, wherein said sump element has a holder for said discharge tube, and said holder forms a seat or fitting for said discharge tube.
 8. The modular tank system according to claim 1, wherein said sump element has a holder for said discharge tube, and said holder has a chamfer allowing said discharge tube to be pushed into said holder.
 9. The modular tank system according to claim 1, wherein said sump element is formed in one piece.
 10. A motor vehicle, comprising: a modular tank system according to claim
 1. 